Tubular container with an outer tube and an inner container

ABSTRACT

Tubular container (1) made of a flexible material, which comprises an outer tube (10) and an inner container (30) housed inside the outer tube (10) and intended to come into contact with the packaged product (51). A flexible shoulder (32) of the inner container (30) is secured to a head (12) of the outer tube (10), there remaining an intermediate cavity (7) between the outer tube (10) and the inner container (30). At least one orifice (24) communicates the intermediate cavity (7) with the exterior of the tubular container (1). The head (12) may include a one-way airless valve. The outer tube (10) may recover its shape whilst the inner container (30) remains compressed during the use of the tubular container (1). The outer tube (10) and the inner container (30) are preferably made out of materials that fulfil different requirements. The distal end (36) of the inner container (30) is preferably flared against the outer tube (10).

FIELD OF THE INVENTION

The invention is related to a tubular container made out of a flexible material, for housing cosmetics, food, a medicine or the like, and more particularly to a tubular container that includes an outer tube and an inner container housed inside the outer tube.

PRIOR ART

Use of flexible plastic tubes is widespread in the cosmetics, pharmacy or food sectors. Flexible plastic tubes are characterised by consisting of a hollow body or skirt, intended to contain a product (for example, a cosmetic cream), and a head placed at one end of the skirt and intended to allow the discharge or dosage of the product. The head may be fitted with a neck for providing an outlet to the product, a cap, dosing mechanisms, etc. Once the tube has been filled with a product, the end of the skirt opposite to the head is sealed via heat transfer welding, generally by hot air, hot clamping, ultrasound, etc.

These flexible plastic tubes are obtained through diverse manufacturing methods such as extrusion, co-extrusion, injection moulding, etc. Likewise, diverse methods are known for providing the flexible plastic tubes with any informative or decorative element by including text, graphics, drawings, etc. either directly on them or by incorporating a separate element such as a label. For instance, flexible plastic tubes may be decorated using techniques such as offsetting, flexography, serigraphy, stamping, self-adhesive labels, etc. In injection moulding tube manufacturing processes, the technique known as In-Mould Labelling (IML) is well known in the prior art to provide the tubes with a label.

In spite of the extensive market implementation, the manufacture of flexible plastic tubes presents certain problems that have not yet been resolved.

For example, a first problem consists in the difficulty in selecting the tube manufacturing materials, particularly in injection moulding processes. The materials used must have very special characteristics and fulfil requirements such as being able to be processed, presenting appropriate weldability, impermeability, environmental stress cracking resistance (ESCR), etc. When directed to the food industry, materials must also fulfil strict requirements related to food contact safety, as the tubes on the market must be in direct contact with the packaged product. In the fields of cosmetics, alimentation and pharmacology, materials must fulfil specific suitability requirements such as non-toxicity, global and specific migrations, etc., as the tubes must often be in direct contact with products that are to be ingested or applied onto the body. Normally, these characteristics and the fulfillment of requirements are achieved through the selection and use of polymer compounds and other components, particularly in the case of tubes manufactured by injection moulding. However, obtaining polymeric compounds that fulfil such a variety of requirements, including mechanical requirements, food contact requirements, non-toxicity requirements, processability requirements, etc. is extremely complex and costly. It must also be added that when polymeric compounds are used, it is complicated to maintain and guarantee the properties of the compound due to the tolerance in the fundamental variables (fluidity, density, rigidity, etc.) of the polymers included in the compound. For this reason, it is extremely complex to obtain a polymeric compound that is able to balance all of the properties needed to successfully manufacture and use the tube, particularly when the tube is an injected tube. In addition, the obligation to obtain polymeric compounds that fulfil strict food-contact or non-toxicity requirements directly rules out an important number of polymers for their use in preparing the compounds. This further hinders the design of the polymeric compounds.

A second problem is related to a type of tube known in the prior art, which is actually made up of two tubes, one inside the other. The solution of having one tube inside another is usually used to obtain an airless container, i.e. a container that prevents the entry of air inside the container in order to improve the preservation of the packaged product (for example, products such as creams without additives, serums, vitamin C, etc.). This solution is also typically used to resolve the effect of the tube collapsing with use. In this type of tubular containers, both the inner and the outer tube are fitted with a skirt and a head having an outlet neck. The inner and outer tubes are joined by their outlet necks. This solution presents flaws when obtaining a high restitution rate (capacity to deliver all of the contents of the tube), as the tube cannot fully collapse due to the high level of rigidity of the head of the inner tube.

A third problem is related to the sealing of double-tube tubular containers, such as those mentioned in the previous paragraph or such as bi-product containers (tubular containers made up of an inner tube and an outer tube and which contain two different products, where the outer tube has a head with a special configuration with two output orifices for the two products, so that the two products are simultaneously released and mix together at the exact time of their application). For the assembly of the aforementioned double-tube containers, the skirt of the inner tube and the skirt of the outer tube have a significant difference in diameter in order to be able to assemble the inner tube inside the outer tube. This means that, when the end of the skirts are flattened for their joint sealing, a perfect sealing between the skirts of the inner and outer tubes is not achieved, and thus sealing faults occur. More specifically, in the central area, the sealing has four wall thicknesses, whilst there are only two at the sides. On compressing the clamps, the walls are welded at the correct pressure in the area of the four walls, whereas pressure is insufficient in the area of the two walls, leading to a poor welding in this area. Furthermore, this looseness hinders the introduction of the welding nozzle, which must be very precisely adjusted inside the tube.

The present invention aims to provide a new design of tubular container that solves at least one of the aforementioned problems.

BRIEF DESCRIPTION OF THE INVENTION

An object of the invention is a tubular container made out of flexible material for housing a cosmetic, food, a medicine or the like, and a method of manufacturing said flexible tubular container. The tubular container comprises an outer tube and an inner container. The outer tube comprises a skirt and a head, wherein the head generally includes, amongst others, a neck, a thread, etc. The inner container, in turn, is fitted with a skirt and, in preferred embodiments of the invention, a shoulder at the proximal end of the skirt. The shoulder is an open cap, i.e. a cap that has an orifice and thus does not entirely close the proximal end of the skirt of the inner container. This shoulder is flexible or deformable, preferably presenting a plastic type deformation. The inner container is housed inside the outer tube, and the shoulder of the inner container is secured to the interior of the head of the outer tube preferably in a sealed manner so that the shoulder of the inner container provides fluidtightness to the inner container once the proximal end of the tubular container has been sealed. Therefore, the inner container does not have a tube head typical of conventional flexible tubes (with neck, thread, etc.); instead, on welding to the outer tube, the inner container uses the neck, thread, etc. of the head of the outer tube to discharge its contents. In other words, the inner container shares or uses the neck of the head of the outer tube. In addition, the shoulder preferably presents a high deformation capacity without jeopardising the welding of the shoulder to the head of the inner container. Furthermore, the shoulder is preferably made out of a laminated complex material (aluminium or other) that is the same or similar to the skirt of the inner container, presenting cost advantages and a very high deformation capacity (the deformation being plastic and hence avoiding shape recovery and guaranteeing the permanent collapse of the inner container).

A gap is defined between the inner container and the outer tube. Preferably, the tubular container is capable of recovering its original shape after use, or in other words, after pressing the tubular container to remove the product housed inside it. On the other hand, the inner container preferably remains deformed by means of a one-way valve that prevents air from returning towards the interior of the inner container; Preferably, this one-way valve is placed in the head of the outer tube, in a cap secured to the head of the outer tube or in a further component such as an applicator or a pump. Furthermore, the distal end of the inner container is preferably deformed and widened (or flared) so that it is contiguous and in contact with the distal end of the outer tube. The outer tube and the inner container may be made out of different materials, so that the inner container, intended to remain in contact with the packaged product, fulfils requirements related to this function whilst the outer tube, which remains visible to the exterior, does not need to fulfil said requirements of the inner container, and instead fulfils requirements related to the outer tube's function such as bearing one or more decorative elements, labels, etc.

An initial advantage offered by at least some of the embodiments of the invention and particularly by those in which the materials of the outer tube and the inner container fulfil different requirements, is that the selection of materials is simplified. This solves one of the main problems of injected tubes and to a certain extent, extruded tubes and the rest of the tube manufacturing techniques, which require the use of materials with high requirements and properties. For example, the possibility of using recycled materials is now an option, particularly to manufacture the outer tube, as it can now be guaranteed that these recycled materials do not come into contact with the packaged product and, thus, that the tubular container fulfils prevailing legislation in relation to packaging in the food, pharmacy or cosmetics sector.

An additional advantage, offered by at least some of the embodiments of the invention, consists in that it makes it possible to reduce the thickness of the outer tube in comparison, for instance, with a conventional injected tube not including a double tube version per the present invention, since the outer tube of the present invention has a merely mechanical function and does not need to come into contact with the packaged product. This thickness reduction would not be possible if the product were in contact with the exterior container as its permeability would be affected. By having a smaller wall thickness, the container would be more permeable and therefore it would not appropriately protect the product contained therewithin; in consequence, some of the product components could permeate, and the product's characteristics could vary. In the present invention, the impermeability property required in the tubular container is provided by the inner container, which can be made out of laminated materials (laminated complex materials) that contain an aluminium film or a polymer barrier, or simply a single-layer structure having the necessary impermeability, the permeability of the outer tube being irrelevant. A reduction in the thickness of the wall in the case of injected tubes would not be possible either, as this reduction would significantly affect the complexity of obtaining a good filling of the injection cavity. To resolve this situation, it is known in the plastic injection field that the use of more fluid polymers enables an article with a thinner wall to be manufactured; however, this increase in fluidity normally entails a change in critical properties such as the ESCR resistance.

An additional advantage, offered by at least some of the embodiments of the invention and particularly by those in which the tubular container recovers its exterior shape after use, consists in that the tubular container provides better ergonomics of use. This is due to the fact that, in order to extract the stored product, pressure will always be exerted on an expanded tubular container, i.e. on a container shaped as if it were completely full, resulting in a more comfortable operation for the user's hand. Another advantage of these embodiments is that the tubular container can maintain an unaltered exterior appearance, i.e. it can remain like new in spite of being used repeatedly and therefore can preserve an optimum exterior appearance throughout its useful life. This is the case even in those embodiments in which the tubular container is airless, as it is the inner container that remains deformed whilst the outer tube recovers its original shape.

An additional advantage offered by at least some of the embodiments of the invention and particularly by those in which the shoulder of the inner container is internally secured to the head of the outer tube, consists in that a more effective and resistant securing between both tubes is obtained in comparison to conventional double-tube solutions in which both tubes have a head and in which the two heads of the tubes are assembled to each other. Furthermore, these embodiments also improve the restitution rate in comparison with said conventional double-tube solutions in which the two tubes are secured by their respective heads. This increase in the restitution rate is achieved as existing solutions did not allow for the entire collapsing or almost entire collapsing of the head of the inner container, even though it is manufactured with a smaller thickness than the head of the outer tube; in the tubular container of the present invention, instead, the shoulder of the inner container is flexible, and preferably made out of a laminated plastic or metal-plastic complex material, and is welded to the inner part of the head of the outer tube, enabling its collapsing as a result of the flexibility of the shoulder.

Another advantage offered by at least some of the embodiments of the invention and particularly by those in which the distal end of the inner container is widened, and contiguous to and in contact with the distal end of the outer tube, is that the sealing of the distal end of the tubular container is significantly improved.

BRIEF DESCRIPTION OF THE FIGURES

The details of the invention can be seen in the accompanying figures, which do not intend to limit the scope of the invention:

FIG. 1 shows a cross-sectional front elevation view of an outer tube of a tubular container in accordance with an embodiment of the invention, the outer tube comprising a skirt, a head and two one-way valves.

FIG. 2 shows a cross-sectional front elevation view of a skirt and a shoulder manufactured separately, in order to form an inner container of a tubular container in accordance with an embodiment of the invention.

FIG. 3 shows a cross-sectional front elevation view of the skirt and the shoulder of the previous figure, joined together to form the inner container.

FIG. 4 shows a cross-sectional front elevation view of the inner container being inserted into an inner space of the outer tube.

FIG. 5 shows a cross-sectional front elevation view of the inner container fully inserted in the inner space of the outer tube.

FIG. 6 shows a cross-sectional front elevation view of the distal end of the skirts of the outer and inner tubes in the situation of FIG. 5.

FIG. 7 shows a cross-sectional front elevation view of a conical part being inserted through the distal end of the outer and inner tubes.

FIG. 8 shows a cross-sectional front elevation view of the distal end of the skirts of the outer and inner tubes once the conical part of FIG. 7 has been removed.

FIG. 9 shows a cross-sectional front elevation view of a tubular container formed of the outer tube and the inner container.

FIG. 10 shows an enlarged view of the head of the outer tube and the shoulder of the inner container, and in particular, of a one-way valve arranged in the head of the outer tube in communication with an intermediate cavity between both tubes.

FIG. 11 shows a cross-sectional front elevation view of the tubular container sealed at the distal end thereof and containing a product inside.

FIG. 12 shows an outer perspective view of the tubular container in the situation in FIG. 11.

FIG. 13 shows a cross-sectional front elevation view of the tubular container of FIG. 11, in a situation in which two opposing forces are being applied, compressing the container in order to remove product from its interior.

FIG. 14 shows a cross-sectional front elevation view of the tubular container of FIG. 11, in a subsequent situation in which the forces are no longer being applied and the outer tube has recovered its non-deformed shape whilst the inner container remains deformed.

DETAILED DESCRIPTION OF THE INVENTION

The invention refers to a tubular container made of a flexible material for the housing of a cosmetic, food, medicine or the like, and to a method of manufacture of said flexible tubular container. This type of tubular container is often characterised by comprising a body or hollow skirt intended to contain a product (for example, a cosmetic cream), and a head arranged at one end of the skirt for allowing the discharge or dosage of the product. The head may be fitted with a product outlet neck, a cap, dosing mechanisms, etc. Manufacturers of this type of tubular containers generally supply these tubular containers to product marketers (for example, of cosmetic products) with the head of the container closed, capped, sealed and generally finished, and with the opposite end of the skirt open. Product marketers fill the tubular containers with their product through the open end of the skirt, and then seal said end of the skirt, the tubular container and product contained therein then being ready for sale to the public.

FIG. 9 shows an example of an embodiment of a tubular container (1) made out of flexible materials as per the invention. The tubular container (1), similarly to other flexible tubular containers known in the prior art, comprises a skirt (2) and a head (3). The skirt (2) is an elongated, hollow and optionally cylindrical body, arranged along a central longitudinal axis (4) and having a proximal end (5) and a distal end (6). The head (3) is arranged at the proximal end (5) of the skirt (2) and provides a closure to said proximal end (5). The head (3) of the tubular container may include diverse elements, such as coupling systems for attaching additional parts, perforable partial plugs, means for coupling closing caps of different shapes, dosing caps, dosing pumps, applicators, non-drip systems, non-return systems, etc.

As can be seen in FIG. 9, the tubular container (1) of the present invention comprises an outer tube (10) and an inner container (30) housed inside the outer tube (10).

The outer tube (10), which is illustrated alone in FIG. 1, comprises a skirt (11) and a head (12). The skirt (11) is an elongated, hollow and optionally cylindrical body arranged about a central longitudinal axis (13). The skirt (11) has an inner space (14) and an inner diameter (d1), and also a proximal end (15) and a distal end (16). The head (12), in turn, is arranged at the proximal end (15) of the skirt (11) and closes the outer tube (10) whilst allowing the dosage of a product from inside the tubular container (1). In diverse embodiments of the invention, the head may have different designs or configurations depending on the application or use of the tubular container (1). For example, the head may have a simple outlet orifice and an outer thread for the coupling of a threaded cap. In other embodiments, the head may have a closure system coupled to the head, such as, for example, a cap, a dosage pump or other. In the present embodiment, the head (12) comprises a shoulder (17), a generally cylindrical platform (18) extending from the shoulder (17), and a threaded neck (19) extending from the platform (18) and intended to receive a threaded cap, a pump, an applicator or other piece or mechanism (not shown). The threaded neck (19) ends in a transverse wall (20) provided with an orifice (21). The head (12) delimits an inner space (22), which, in the present embodiment, extends from the inner space (14) of the skirt (11) to the orifice (21) in the transverse wall (20).

Optionally, a one-way valve (23) may be placed in the orifice (21) of the transverse wall (20), the one-way valve being of the type that allows the product to be removed from inside the tube towards the exterior and prevents the return of the product and air from the exterior towards the interior of the tube. For example, the one-way valve (23) shown in the figure comprises a sphere (23 a) that seals against a conical seat (23 b); the sphere (23 a) has axial freedom of movement, enabling the passage of the product contained in the inner space (14, 22) when pressure is exerted on the outer tube (10), and closing the passage of air from the exterior towards the inner space (14, 22) of the tube when this pressure disappears and a depression appears in the interior (as explained later with reference to FIGS. 13 and 14).

In certain embodiments of the present invention, the outer tube (10) may include at least one orifice (24) made in the skirt (11) and/or in the head (12) of the outer tube (10) to provide an air passageway between the exterior of the outer tube (10) and the inner space (14, 22) of the outer tube (10). For example, in the present embodiment, an orifice (24) is provided in the platform (18) of the head (12) of the outer tube (10), communicating the inner space (14, 22) with the exterior space (not numbered). In certain embodiments, such as in the present embodiment, a one-way valve (25) may be housed in the orifice (24), the function of the one-way valve (25) being to allow the intake of air from the exterior of the outer tube (10) towards the inner space (14, 22) through the orifice (24) while preventing the passage of air from the inner space (14, 22) towards the exterior of the outer tube (10) through the orifice (24). For example, the one-way valve (25) of the present embodiment, as shown in the enlarged view of FIG. 10, is formed as a plug inserted in the orifice (24) and fitted with a flexible conical obturator (26) whose distal end (lower end in the figure) opens when the air pressure from the exterior of the tube is greater than the air pressure inside the tube, and closes when the air pressure inside the tube is greater than the air pressure outside the tube. As shown in FIG. 9, the orifice (24) and the one-way valve (25) of the present embodiment are arranged axially, i.e. in the direction of the central longitudinal axis (13), and in an area of the platform (18) adjacent to the shoulder (17).

The outer tube (10) may be decorated using techniques such as offsetting, flexography, serigraphy, stamping, self-adhesive labels, or in-mould labelling (IML).

As shown in FIG. 3, the inner container (30), in turn, comprises a skirt (31) and a shoulder (32). The skirt (31) is an elongated, hollow and optionally cylindrical body, arranged along a central longitudinal axis (33) and having an inner space (34). The skirt (31) of the inner container (30) further presents a proximal end (35), a distal end (36) and an external diameter (d2), wherein the external diameter (d2) is preferably slightly less than the internal diameter (d1) of the skirt (11) of the outer tube (10). The shoulder (32) of the inner container (30) is placed at the proximal end (35) of the skirt (31) and is formed as a wall that partially closes said proximal end of the skirt (31) and ends in an edge (38). The shoulder (32) is flexible and has an inner space (39). In turn, the edge (38) delimits an orifice (37) that communicates the inner space (39) with the exterior of the inner container (30). Preferably, as is the case in the present embodiment, the wall that forms the shoulder (32) is substantially frustoconical, and the edge (38) and the hole (37) are concentric and their centre is arranged on the central longitudinal axis (33) of the inner container (30). In certain embodiments, the shoulder (32) may have a constant thickness. In other embodiments, such as the one disclosed herein, the edge (38) has a greater thickness than the rest of the shoulder (32). Embodiments are also contemplated in which the shoulder (32) comprises at least one notch or area with a reduced thickness (not shown), for instance in the shape of a ring arranged around the central longitudinal axis (33), whose function is detailed hereinafter.

As previously mentioned, the inner container (30) is arranged inside the outer tube (10), i.e. within the inner space (14) of the skirt (11) and within part of the inner space (22) of the head (12) of the outer tube (10). As shown in FIG. 9, the shoulder (32) of the inner container (30) is in contact with the head (12) of the outer tube (10) throughout the full perimeter of the shoulder (32), said contact being fluidtight by means of a sealed union (40) defined between the shoulder (32) and the head (12). Preferably, this sealed union (40) between the shoulder (32) and the head (12) consists of a welded union. The sealed union (40) prevents the passage of fluids between the edge (38) of the shoulder (32) of the inner container (30) and the head (12) of the outer tube (10); the passage of fluid is prevented throughout the entire sealed union (40), which extends 360° around the central longitudinal axis (4) of the tubular container (1).

As shown, the sealed union (40) is placed in a radially-intermediate area of the head (12) of the outer tube (10), radially closer to the central longitudinal axis (4) than the skirt (31) of the inner container (30) and, more specifically, on an edge (27) of the platform (18) adjacent to the inner space (22). In certain embodiments, this edge (27) of the head (12) of the outer tube (10) may be provided with a seat or protrusion extending towards the inner space (22), not shown, whose function is detailed hereinafter.

Furthermore, as previously mentioned, the external diameter (d2) of the skirt (31) of the inner container (30) is slightly less than the internal diameter (d1) of the skirt (11) of the outer tube (10), so that a gap is defined between the skirt (11) of the outer tube (10) and the skirt (31) of the inner container (30). This diameter difference is such that it enables that, when the inner container (30) is flared as will be explained hereinafter with reference to FIGS. 7 and 8, the skirt (31) of the inner container (30) has sufficient deformation capacity to adjust to the internal diameter (d1) of the skirt (11) of the outer tube (10).

The distal ends (16, 36) of the outer tube (10) and the inner container (30) are arranged at the distal end (6) of the skirt (2) of the tubular container (1). As shown in the enlarged view of FIG. 8, the skirt (31) of the inner container (30) comprises a widened area (41) at the distal end (36) of the skirt (31). A length (h2) of the widened area (41) remains contiguous to and in contact with the distal end (16) of the skirt (11) of the outer tube (10), preferably throughout the full perimeter of the skirt (11) of the outer tube (10) around the central longitudinal axis (4) of the tubular container (1).

In certain embodiments, the distal ends (16, 36) of the skirts (11, 31) of the outer tube (10) and the inner container (30) are welded or adhered to each other in the contact area having length (h2). The welding or adhering may span the entire perimeter around the central longitudinal axis (4) or be intermittent. The welding or adhering may span all or part of the length (h2). The purpose of the welding or adhering is two-fold. An initial function is that the welding or adhering ensures that the distal ends (16, 36) of the skirts (11, 31) of the outer tube (10) and inner container (30) remain in contact and contiguous until the time of sealing the distal end (6) of the tubular container (1) once the container has been filled with a product. It must be taken into account that, from the time of manufacturing the tubular container (1) of FIG. 9 until it is filled with a product and sealed at its distal end (6), quite some time may pass and the tubular container (1) may be subjected to transportation, storage, handling, etc., which may cause undesired mechanical actions on the tubular container (1). The welding or adhering help ensure that contact along the length (h2) is maintained in spite of these potential mechanical actions, and that a close bond is achieved between the inner container (30) and the outer tube (10) during the final sealing of the distal end (6) of the tubular container (1). A second function of the welding or adhering, in the specific case in which the welding or adhering is along the entire perimeter, consists in ensuring that the interior wall of the distal end (16) of the skirt (11) of the outer tube (10) is perfectly welded to the exterior wall of the distal end (36) of the skirt (31) of the inner container (30). In this way, on sealing the distal end (6) of the tubular container (1) once the container has been filled with a product, the product marketer must only be concerned about the proper welding of the inner container (30), as the outer tube (10) is supplied pre-welded. From the point of view of the product marketer who needs to fill the container and seal the distal end (6), this solution contributes to the tubular container (1) behaving as if it were a single-layer tube, which significantly simplifies the sealing of the distal end (6), as commonly used systems introduce a nozzle with very reduced tolerances with respect to the walls of the tubes.

As shown in FIG. 8, the aforementioned intermediate cavity (7) is delimited above the widened area (41). Therefore, as shown in FIGS. 8 and 9, the intermediate cavity (7) is delimited by the head (12) of the outer tube (10), the shoulder (32) of the inner container (30) and the skirts (11, 31) of the outer tube (10) and the inner container (30).

In certain embodiments, such as the one shown in the figures, the outer tube (10) and the inner container (30) are formed with dimensions such that the distal end (16) of the skirt (11) of the outer tube (10) protrudes from the distal end (36) of the skirt (31) of the inner container (30) a length (h1), as shown in FIG. 8.

An example of a method of manufacturing a tubular container as per the invention, for the manufacture of the previous tubular container (1), is detailed below. Then, the methods of use of the tubular container (1) by the product marketer and by the final user are detailed in order to explain the advantageous effects of the invention.

FIGS. 1 to 10 show a manufacturing sequence of the tubular container (1) as per an example of the embodiment of the manufacturing as per the invention.

In an initial step of the procedure, the aforementioned outer tube (10) having a skirt (11) and head (12), illustrated in FIG. 1, is manufactured. The outer tube (10) can be manufactured in one or various phases by any conventional technique known in the field of flexible tubular container manufacturing. For example, the outer tube (10) may be manufactured by extrusion of the skirt (11) and subsequent over-injection of the head (12). In other embodiments, the outer tube (10) can be produced through injection moulding of the skirt (11) and a subsequent over-injection moulding of the head (12) onto the skirt (11). In another example, the entire outer tube (10) can be produced by injection moulding the skirt (11) and the head (12) jointly. The outer tube (10) may be manufactured from a formulation comprising one or more plastic materials such as polypropylene, polyethylene, copolymers, etc. The manufacture of the outer tube (10) may comprise its decoration using techniques such as offsetting, flexography, serigraphy, stamping, self-adhesive labels, or in-mould labelling (IML).

In another initial step of the procedure, which may be performed before, after or in parallel with the previous step, the inner container (30) having a skirt (31) and a shoulder (32) is manufactured. The skirt (31) and the shoulder (32) may be made out of plastic, metal or combinations thereof. The skirt (31) and the shoulder (32) may be manufactured together or, alternatively, may be manufactured separately and then joined together, as shown in FIGS. 2 and 3. More specifically, and as way of example, the skirt (31) may be obtained from a plastic film (e.g., polyethylene), from a metal-plastic complex film (e.g., a layer of aluminium with an outer coating or an inner layer of polyethylene or polypropylene, and the necessary adhesives to make the union between layers possible), from a plastic complex film (e.g., a layer of EVOH with an outer coating and/or an inner layer of polyethylene or polypropylene, also using the necessary adhesives) or by other plastic transformation techniques such as extrusion or injection. In case of using a film, the film is deformed or flexed until a tubular, for example cylindrical, shape is obtained. Then, the opposing longitudinal edges of the film are welded or sealed to obtain a tubular sleeve. Welding is performed by generating heat in the welding area. The heat makes the polymers in the opposing longitudinal edges melt and adhere to each other. This manufacturing method is known and used in the manufacture of laminated tubes intended to contain, for example, toothpaste. Heat generation may be carried out using a conventional resistance system, or by a high frequency magnetic field (in the case of using a metal-plastic film), among others. Finally, the skirt (31) is obtained by cutting a predetermined length of the tubular sleeve. Continuing with the example, the shoulder (32) of the inner container (30), in turn, may be made from a plastic film (e.g., polyethylene), from a metal-plastic film (e.g., a layer of aluminium with an outer coating and/or an inner layer of polyethylene or polypropylene, also using the necessary adhesives to make the union between layers possible), from a plastic complex film (e.g., a layer of EVOH with an outer coating and/or an inner layer of polyethylene or polypropylene, also using the necessary adhesives). Portions of the film are cut and an orifice is made in each portion. Then, the portions are placed in a mould and a pressure or stamping is applied, providing the shoulder with a three-dimensional cylindrical-conical shape such as that shown in the figures, where the orifice of each portion constitutes the orifice (37) of the shoulder (32). Although a frustoconical shoulder (32) has been shown herein, alternative embodiments are contemplated in which the shape of the shoulder (32) may vary.

Once the skirt (31) and the shoulder (32) of the inner container (30) are obtained, the shoulder (32) is welded to the proximal end (35) of the skirt (31), as shown in FIG. 3, thereby attaching them. The welding can be performed for instance by hot air, conduction, ultrasound, etc. The welding may also be performed by a high frequency magnetic field, in case that both the skirt (31) and the shoulder (32) are made out of a combination of plastic and metal.

Once the inner container (30) has been obtained, the inner container (30) is inserted inside the outer tube (10) as shown in FIG. 4. More specifically, the shoulder (32) of the inner container (30) is inserted through the open distal end (16 of the skirt (11) of the outer tube (10) and the inner container (30) is advanced inside the outer tube (10) and along the inner space (14) of the outer tube (10). Eventually, as shown in FIG. 5, the shoulder (32) of the inner container (30), and more specifically the edge (38) that surrounds the orifice (37), comes into contact with the interior wall of the head (12) of the outer tube (10), and more specifically the interior wall of the platform (18).

The shoulder (32) of the inner container (30) is then welded to the head (12) of the outer tube (10), for instance by hot air, conduction or high frequency (in case the shoulder (32) and/or the head (12) are made out of a combination of plastic and metal). As previously explained, the welding provides a sealed union (40) between the edge (38) of the shoulder (32) of the inner container (30) and the interior wall of the head (12) of the outer tube (10) is obtained, in addition to securing the outer tube (10) and the inner container (30) to each other.

As shown in FIG. 6, once the inner container (30) has been inserted into and secured to the outer tube (10), the distal ends (16, 36) of the skirts (11, 31) at the opposite end of the outer tube (10) and the inner container (30) are radially separated from each other by a gap or distance (r1). This distance (r1) is substantially equal to half of the difference between the internal diameter (d1) of the skirt (11) of the outer tube (10) and the external diameter (d2) of the skirt (31) of the inner container (30). In addition, the distal end (16) of the skirt (11) of the outer tube (10) may protrude a length (h1) with respect to the distal end (36) of the skirt (31) of the inner container (30), as shown in the figures. However, alternative embodiments are contemplated in which the distal end (16) of the skirt (11) of the outer tube (10) does not protrude from the distal end (36) of the skirt (31), i.e. in which the length (h1) is zero.

Then, as illustrated in FIGS. 7 and 8, an additional optional step is performed consisting in flaring the distal end (36) of the inner container (30). In this step, the inner container (30), and optionally the outer tube (10), is subjected to a deformation that causes the widening of the open distal end (36) of the skirt (31) of the inner container (30) until its external diameter (d2) is substantially the same as the internal diameter (d1) of the skirt (11) of the outer tube (10) and therefore the distal end (36) of the skirt (31) of the inner container (30) internally rests against the distal end (16) of the skirt (11) of the outer tube (10). The deforming may be carried out, for example, by axially inserting a part with a diminishing diameter or a conical part (50) in the open distal end (36) of the skirt (31) of the inner container (30) up to a predefined depth. In certain embodiments, heat may be applied together with the deformation, causing a fusion of the distal ends (16, 36); in other embodiments, the deformation can be carried out without applying heat, causing the distal ends (16, 36) to become contiguous and in contact. Once the conical part (50) has deformed the distal end (36) of the skirt (31) of the inner container (30), the conical part (50) is removed. In some embodiments, such as the embodiment depicted herein, the distal end (16) of the skirt (11) of the outer tube (10) does not deform. In other embodiments, the distal end (16) of the skirt (11) of the outer tube (10) deforms, and can recover its original, cylindrical shape once the conical part (50) is removed. In yet other embodiments, the distal end (16) of the skirt (11) of the outer tube (10) deforms and does not recover its original, cylindrical shape once the conical part (50) is removed. In any case, once the conical part (50) has been removed, as shown in FIG. 8, a length (h2) of the distal end (36) of the skirt (31) of the inner container (30) is attached against and in contact with the skirt (11) of the outer tube (10). In some embodiments, simultaneously or subsequently to the deformation, a welding or an adhesive is applied along all or part of the perimeter of the walls of the distal ends (16, 36) of the skirts (11, 31), so that these distal ends (16, 36) are not only made contiguous but also attached along part of or the entire perimeter.

Once the distal ends (16, 36) of the skirts (11, 31) of the outer tube (10) and the inner container (30) are made contiguous by deformation, and optionally attached together by welding or adhering along all or part of the perimeter, the tubular container (1) of FIG. 9 is obtained. This tubular container (1) is characterised in that it has an outer tube (10) intended to remain visible and be touched by the consumer, and an inner container (30) intended to come into contact with the product that will be stored inside the tubular container (1).

Finally, if not done so yet, a lid (not shown) or any other optional extra element is added to the tubular container (1). The tubular container (1) is then delivered to a product marketer, for example a cosmetic product marketer, in order for them to fill the tubular container (1) with their products.

For the product marketer, the tubular container (1) as per the invention, while being made up of two tubes (the outer tube (10) and the inner container (30)), has the outer appearance of a conventional tubular container and, more importantly, can be filled and sealed in the same way as a conventional tubular container. The head (12) of the outer tube (10) forms the head (3) of the tubular container (1), whilst the skirts (11, 31) form the skirt (2) of the tubular container (1). The distal ends (16, 36) of the skirts (11, 31) of the outer tube (10) and the inner container (30) are contiguous to and contacting each other, and thus a single opening is provided at the distal end (6) of the skirt (2) of the tubular container (1) communicating with a single inner space of the tubular container (1) (the single inner space being the inner space (34) of the inner container (30)), enabling the filling of the tubular container (1) in a conventional way.

The product marketer (e.g., a cosmetic product marketer) fills the tubular container (1) with a certain product (51) (shown in FIGS. 11, 13 and 14), for instance a cream, feeding the product (51) into the inner space (34, 39) of the inner container (30) through the open distal end (6) of the tubular container (1). Then, as shown in FIG. 11, the distal end (6) of the skirt (2) of the tubular container (1) is welded for instance by applying heat, high frequency, an adhesive, etc. to the skirt (2); pressure is then applied to this distal end (6) of the skirt (2), flattening the distal end (6) and causing it to be sealed in a straight seal, as shown in FIG. 12. More specifically, the sealing is carried out along a band of the distal end (6) having a height (h3) that spans along part or all of the length (h2) of the widened area (41) of the distal end (36) of the skirt (31) of the inner container (30) and further, along the excess length (h1) of the skirt (11) of the outer tube (10), if there is such excess length (h1). This ensures an intimate and resistant bonding between the two skirts (11, 31) throughout the full perimeter of the skirts (11, 31) along the widened area (41) and, optionally, a sealing of the end of the skirt (11) of the outer tube (10) onto itself along the excess length (h1) of the skirt (11) of the outer tube (10). Once welded, the product (51) is housed in the inner space of the tubular container (1), and more specifically in the inner space (34, 39) of the inner container (30), as shown in FIG. 11.

FIG. 13 shows the process of extracting product (51) from the interior of the tubular container (1) by a user. As shown, when a user wishes to dispense some of the product (51) from the interior of the tubular container (1), the user normally applies two opposite lateral forces (F) with the help of the user's fingers. The forces (F) cause the outer tube (10) to collapse towards the inside of the skirt (11) and the pressure in the intermediate cavity (7) between the outer tube (10) and the inner container (30) to increase. In the present embodiment, the one-way valve (25) of the outer tube (10) prevents the release of air from the intermediate cavity (7){tilde over (n)} thus, the collapsing of the skirt (11) and the pressure increase in the intermediate cavity (7) cause the inner container (30), and more specifically the skirt (31) of the inner container (30), to compress. In alternative embodiments, one or more orifices in the outer tube (10), communicated with the intermediate cavity (7) and preferably devoid of valves may allow the outlet of air on compressing the outer tube (10) and thus allow the outer tube (10) to come into contact and push the inner container (30), causing the compression of the skirt (31) of the inner container (30). As the skirt (31) of the inner container (30) compresses, the edge (38) of the shoulder (32) of the inner container (30) remains welded against the head (12) of the outer tube (10). If the shoulder (32) of the inner container (30) includes one or more notches or areas with a reduced thickness, these notches further facilitate the shoulder (32) to flex downwards, if necessary, on compressing the skirt (31) without the flexing the edge (38) of the shoulder (32) to excessively pull on the head (12) of the outer tube (10).

Compression of the skirt (31) of the inner container (30) causes a pressure increase in the inner space (34, 39) of the inner container (30). When the pressure increase is sufficient, the product (51) begins to be removed through the orifice (37) in the shoulder (32) of the inner container (30), the inner space (22) of the head (12) of the outer tube (10) and the one-way valve (23) in the head (12) of the outer tube (10). When the user stops applying the forces (F), the skirt (31) of the outer tube (30), which is elastic and tends to recover its original non-deformed shape, begins to open outwards, creating a vacuum in the intermediate cavity (7). This vacuum leads to air entering from the exterior through the one-way valve (25) or, in alternative embodiments, through one or more valveless orifices in the outer tube (10) and communicated with the intermediate cavity (7). The intake of air in the intermediate cavity (7) helps the skirt (11) of the outer tube (10) recover its original shape, as shown in FIG. 14. The one-way valve (23) of the head (12) of the outer tube (10) prevents the return of the product (51) or outside air towards the inner space (22) of the head (12) of the outer tube (10) and therefore towards the inner space (34, 39) of the inner container (30). In consequence, the inner container (30) remains in a deformed position, as shown in FIG. 14. The fact that the sealed union (40) between the shoulder (32) of the inner container (30) and the head (12) of the outer tube (10) is made in an intermediate area of the head (12) of the outer tube (10) helps the deformed inner container (30) not to pull on the non-deformed outer tube (10), so that both can relaxedly maintain their deformed and non-deformed position.

In other words, the tubular container (1) described heretofore is capable of maintaining its exterior appearance intact after use (by recovering its non-deformed appearance after pressing as shown in FIGS. 12 and 14), and also makes up an airless container, with the associated advantages (mainly that the product (51) remains isolated from the exterior air, improving its conservation and extending its useful life).

Repeated use of the tubular container (1) will produce the increasing compression of the inner container (30), whilst the outer tube (10) recovers as explained. Due to the fact that the shoulder (32) is highly deformable and is only joined to the head (12) of the outer tube (10) by a sealed perimeter band (the sealed union (40)), the shoulder (32) may be deformed and folded inwards almost freely, leading to high levels of collapsing and restitution rates. If the edge (27) of the head (12) is protruding or has a seat in which the sealed union (40) is located, the folding of the shoulder (32) together with the skirt (31) of the inner container (30) when discharging the product (51) may be favoured, further increasing the collapsing of the inner container (30) and the restitution rate of the tubular container (1).

As previously mentioned, in alternative embodiments, the intermediate cavity (7) is communicated with the exterior through one or more permanent orifices (i.e. permanently-open orifices) in the outer tube (10), for example in the shoulder (17) or in the skirt (11) of the outer tube (10). This leads to a less costly tubular container, as there is no one-way valve (25) and its assembly is not necessary. The number and/or dimensions of the orifices must provide effective and comfortable balance to the loss of pressure through the intermediate chamber and the speed of recovery of the original shape of the outer tube.

As far as the materials used to produce the outer tube (10) and the inner container (30) of the tubular container (1) are concerned, it has been mentioned heretofore that both the outer tube (10) and the inner container (30) may be made out of formulations of plastic materials, plastic complex materials, metal-plastic complex materials, one or more layers of a textile material, one or more layers of paper, combinations thereof, etc. In short, it is contemplated that the outer tube (10) and the inner container (30) may be made out of any material or formulation applicable for tubes of flexible materials, such as polypropylene, polyethylene, polyolefin copolymers, aluminium laminated complex materials, EVOH laminated complex materials, etc. However, in a preferred embodiment of the invention, the outer tube (10) is made out of a plastic formulation and transformed using injection moulding techniques, whilst the inner container (30) is preferably made out of a plastic or metal-plastic formulation, and more specifically of plastic or metal-plastic laminated complex materials transformed through shaping techniques.

Preferably, the material or materials out of which the inner container (30) is made satisfy one or more of the following requirements: impermeability requirements, ESCR resistance requirements, anti-delaminating requirements, food contact requirements, pharmacopeia requirements, flexibility requirements, deformability requirements, etc. This enables the inner container (30) to fulfil the functions described in the present disclosure. In turn, the material or materials out of which the outer tube (10) is made satisfy one or more different requirements, such as processability requirements, surface appearance requirements, printability requirements (ability to be printed on), mechanical rigidity requirements (having a mechanical rigidity over a threshold value), etc.; in addition, the material or materials out of which the outer tube (10) is made may consist of recycled materials.

Preferably, the material or materials out of which the outer tube (10) is made do not fulfil the requirements of the material or materials out of which the inner container (30) is made. In other words, the outer tube (10) preferably does not fulfil the requirements of the inner container (30). For example, the materials of the outer tube (10) preferably do not fulfil the impermeability, ESCR resistance, weldability, anti-delaminating, food contact, pharmacopeia, flexibility and/or deformability requirements that the materials of the inner container (30) do fulfil.

Preferably, the material or materials out of which the inner container (30) is made do not fulfil the requirements of the material or materials out of which the outer tube (10) is made. In other words, the inner container (30) preferably does not fulfil the requirements of the outer tube (10). For example, the materials of the inner container (30) preferably do not fulfil the processability, surface appearance, printability, mechanical rigidity and/or weldability requirements that the materials of the outer tube (10) do fulfil.

This separation of functional requirements into two components—the inner container (30) and the outer tube (10)—means neither one of these components must fulfil all of the requirements simultaneously, and therefore facilitates the selection of materials for each tube. This simplifies manufacturing and increases the quality of the final tubular container (1) (quality being understood to be the ability of the tubular container (1) to fulfil its functional requirements during its useful life).

In summary, the problem of the non-complete restitution of double-tube airless containers is solved by using an inner container fitted with a skirt and a shoulder in the form of a wall with a diminishing diameter, which presents greater deformability in comparison with the deformation of the head of inner tubes known in the prior art.

On the other hand, the problem of achieving a proper sealing between the distal ends of an outer tube and an inner container arranged inside the outer tube is solved by widening or flaring the distal end of the inner container until it is contiguous and in contact with the distal end of the outer tube, and then sealing both contiguous distal ends, thereby forming an intimate union between said distal ends along their full perimeter. It is contemplated that this solution may be used in alternative tubular containers to the one illustrated herein, for example in tubular containers in which both the outer tube and the inner container comprise a respective skirt and a respective head.

Furthermore, the problem of the complexity in selecting materials is solved through the creation of a tubular container fitted with an inner container intended to remain hidden and in contact with the product to be stored, and an outer tube intended to be visible, where the materials of each of these tubes fulfil different functional requirements and, most importantly, the outer tube does not fulfil the requirements of the inner container. It is contemplated that this solution may be used in alternative tubular containers to the one illustrated herein, for example in tubular containers in which both the outer tube and the inner container comprise a respective skirt and a respective head. 

1. Tubular container (1) of flexible material, comprising: an outer tube (10), having a skirt (11) and a head (12), wherein the skirt (11) has a proximal end (15) and a distal end (16), wherein the head (12) extends from the proximal end (15) of the skirt (11), and wherein the skirt (11) and the head (12) delimit an inner space (14, 22) that can communicate with the exterior of the outer tube (10) through an orifice (21) in the head (12); an inner container (30), having a skirt (31) and a flexible shoulder (32), wherein the skirt (31) has a proximal end (35) and a distal end (16), wherein the shoulder (32) extends from the proximal end (35) of the skirt (31), and where the skirt (31) and the shoulder (32) delimit an inner space (34, 39) and the shoulder (32) ends in an edge (38) that delimits an orifice (37) that is communicated with the inner space (34, 39); wherein the inner container (30) is arranged in the inner space (14, 22) of the outer tube (10), and the shoulder (32) of the inner container (30) is secured to the head (12) of the outer tube (10), the orifice (21) of the head (12) of the outer tube (10) being communicated with the inner space (34, 39) of the inner container (30).
 2. Tubular container (1), in accordance with claim 1, characterised in that it comprises at least one one-way valve (23) that enables a fluid to exit the inner space (34, 39) of the inner container (30) to the exterior of the outer tube (10) and that prevents the entry of air from the exterior of the outer tube (10) to the inner space (34, 39) of the inner container.
 3. Tubular container (1), in accordance with claim 2, characterised in that the one-way valve (23) is arranged in the hole (21) of the head (12) of the outer tube (10).
 4. Tubular container (1), in accordance with claim 1, characterised in that the skirt (31) of the inner container (30) does not protrude from the skirt (11) of the outer tube (10).
 5. Tubular container (1), in accordance with claim 1, characterised in that the shoulder (32) of the inner container (30) is secured to the head (12) of the outer tube (10) by the edge (38) of the shoulder (32).
 6. Tubular container (1), in accordance with claim 1, characterised in that the shoulder (32) is secured to the head (12) of the outer tube (10) through a sealed union (40) extending continuously along a full perimeter around a central longitudinal axis (4) of the tubular container (1).
 7. Tubular container (1), in accordance with claim 1, characterised in that an intermediate cavity (7) is delimited between the outer tube (10) and the inner container (30).
 8. Tubular container (1), in accordance with claim 7, characterised in that the shoulder (32) is secured to the head (12) of the outer tube (10) through a sealed union (40) extending continuously along a full perimeter around a central longitudinal axis (4) of the tubular container (1).
 9. Tubular container (1), in accordance with claim 8, characterised in that the intermediate cavity (7) is radially exterior to the sealed union (40) with respect to the central longitudinal axis (4).
 10. Tubular container (1), in accordance with claim 9, characterised in that the shoulder (32) of the inner container (30) is only joined to the head (12) of the outer tube (10) along the sealed union (40), whereby the rest of the shoulder (32) is radially exterior to the sealed union (40) and separated from the outer tube (10).
 11. Tubular container (1), in accordance with claim 8, characterised in that the intermediate cavity (7) extends from the sealed union (40) to the distal end (36) of the skirt (31) throughout the full perimeter of the skirt (31) and the shoulder (32) around a central longitudinal axis (4) of the tubular container (1).
 12. Tubular container (1), in accordance with claim 11, characterised in that the distal end (36) of the skirt (31) of the inner container (30) is in contact with the distal end (16) of the skirt (11) of the outer tube (10).
 13. Tubular container (1), in accordance with claim 9, characterised in that the distal end (36) of the skirt (31) of the inner container (30) is in contact with the distal end (16) of the skirt (11) of the outer tube (10) throughout an entire perimeter around the central longitudinal axis (4).
 14. Tubular container (1), in accordance with claim 10, characterised in that the distal end (36) of the skirt (31) of the inner container (30) is secured to the distal end (16) of the skirt (11) of the outer tube (10) along at least part of said perimeter.
 15. Tubular container (1), in accordance with claim 7, characterised in that the outer tube (10) comprises at least one orifice (24) communicating the intermediate cavity (7) with the exterior of the outer tube (10).
 16. Tubular container (1), in accordance with claim 15, characterised in that a one-way valve (25) is arranged in the orifice (24), the one-way valve (25) allowing the entry of air from the exterior of the outer tube (10) to the intermediate cavity (7) and preventing the exit of air from the intermediate cavity (7) to the exterior of the outer tube (10).
 17. Tubular container (1), in accordance with claim 16, characterised in that the intermediate cavity (7), the orifice (24) and the one-way valve (25) are radially exterior to the sealed union (40) with respect to the central longitudinal axis (4).
 18. Method of manufacturing a tubular container (1) of flexible material, comprising the steps of: obtaining an outer tube (10) having a skirt (11) and a head (12), wherein the skirt (11) has a proximal end (15) and a distal end (16), wherein the head (12) extends from the proximal end (15) of the skirt (11), and wherein the skirt (11) and the head (12) delimit an inner space (14, 22) that can communicate with the exterior of the outer tube (10) through an orifice (21) in the head (12); obtaining an inner container (30) having a skirt (31) and a flexible shoulder (32), wherein the skirt (31) has a proximal end (35) and a distal end (16), wherein the shoulder (32) extends from the proximal end (35) of the skirt (31), and wherein the skirt (31) and the shoulder (32) delimit an inner space (34, 39) and the shoulder (32) ends in an edge (38) that delimits an orifice (37) that is communicated with the inner space (34, 39); wherein inserting the inner container (30) into the inner space (14, 22) of the outer tube (10), and securing the shoulder (32) of the inner container (30) to the head (12) of the outer tube (10), the orifice (21) of the head (12) of the outer tube (10) communicating with the inner space (34, 39) of the inner container (30).
 19. Method, in accordance with claim 18, characterised in that the step of obtaining an outer tube (10) comprises obtaining the skirt (11) of the outer tube (10) by extrusion and forming the head (12) of the outer tube (10) through over-injection moulding onto the skirt (11) of the outer tube (10).
 20. Method, in accordance with claim 18, characterised in that the step of obtaining an outer tube (10) comprises obtaining the skirt (11) of the outer tube (10) by injection moulding and forming the head (12) of the outer tube (10) through over-injection moulding onto the skirt (11) of the outer tube (10).
 21. Method, in accordance with claim 18, characterised in that the step of obtaining an inner container (30) comprises obtaining the outer tube (10) through a joint injection moulding of the skirt (11) and the head (12) of the outer tube (10).
 22. Method, in accordance with claim 18, characterised in that the step of obtaining an inner container (30) comprises obtaining the skirt (31) of the inner container (30) by extrusion and forming the shoulder (32) of the inner container (30) through over-injection moulding onto the skirt (31) of the inner container (30).
 23. Method, in accordance with claim 18, characterised in that the step of obtaining an inner container (30) comprises obtaining the skirt (31) of the inner container (30) by injection moulding and forming the shoulder (32) of the inner container (30) through over-injection moulding onto the skirt (31) of the inner container (30).
 24. Method, in accordance with claim 18, characterised in that the step of obtaining an inner container (30) comprises obtaining the inner container (30) through a joint injection moulding of the skirt (31) and the shoulder (32) of the inner container (30).
 25. Method, in accordance with claim 18, characterised in that the step of obtaining an inner container (30) comprises obtaining a first film of a plastic or metal-plastic complex material, deforming the first film until a tubular shape is obtained, sealing the adjacent edges of the tubular shape to maintain the tubular shape, thereby obtaining the skirt (31) of the inner container (30); obtaining a second film of a plastic or metal-plastic complex material; making an orifice in the second film; stamping the second provided with said orifice, thereby forming the shoulder (32) of the inner container (30); and securing the shoulder (32) of the inner container (30) to the skirt (31) of the inner container (30).
 26. Tubular container (1) of flexible material, comprising: an outer tube (10), comprising a skirt (11) and a head (12), wherein the skirt (11) has a proximal end (15) and a distal end (16), wherein the head (12) extends from the proximal end (15) of the skirt (11), and wherein the skirt (11) and the head (12) delimit an inner space (14, 22) that can communicate with the exterior of the outer tube (10) through an orifice (21) in the head (12); an inner container (30), comprising a skirt (31) having a proximal end (35) and a distal end (16); wherein the inner container (30) is arranged in the inner space (14, 22) of the outer tube (10), and the distal end (36) of the skirt (31) of the inner container (30) is flared and in contact with the distal end (16) of the skirt (11) of the outer tube (10).
 27. Tubular container (1), in accordance with claim 26, characterised in that the distal end (36) of the skirt (31) of the inner container (30) is flared and in contact with the distal end (16) of the skirt (11) of the outer tube (10) along a full perimeter around a central longitudinal axis (4) of the tubular container (1).
 28. Tubular container (1), in accordance with claim 26, characterised in that the distal end (36) of the skirt (31) of the inner container (30) is arranged flush with the distal end (16) of the skirt (11) of the outer tube (10).
 29. Tubular container (1), in accordance with claim 26, characterised in that a length (h1) of the distal end (16) of the skirt (11) of the outer tube (10) protrudes from the distal end (36) of the skirt (31) of the inner container (30).
 30. Tubular container (1), in accordance with claim 26, characterised in that the distal end (36) of the skirt (31) of the inner container (30) is secured to the distal end (16) of the skirt (11) of the outer tube (10) in at least part of a perimeter around a central longitudinal axis (4) of the tubular container (1).
 31. Tubular container (1), in accordance with claim 30, characterised in that the distal end (36) of the skirt (31) of the inner container (30) is secured to the distal end (16) of the skirt (11) of the outer tube (10) by welding, an adhesive or a combination thereof.
 32. Method of manufacturing a tubular container (1) of flexible material, comprising the steps of: obtaining an outer tube (10) comprising a skirt (11) and a head (12), wherein the skirt (11) has a proximal end (15) and a distal end (16), wherein the head (12) extends from the proximal end (15) of the skirt (11), and wherein the skirt (11) and the head (12) delimit an inner space (14, 22) that can communicate with the exterior of the outer tube (10) through an orifice (21) in the head (12); obtaining an inner container (30) comprising a skirt (31), wherein the skirt (31) has a proximal end (35) and a distal end (16); inserting the inner container (30) into the inner space (14, 22) of the outer tube (10); and flaring the distal end (36) of the skirt (31) of the inner container (30), the distal end (36) of the skirt (31) of the inner container (30) remaining flared and in contact with the distal end (16) of the skirt (11) of the outer tube (10).
 33. Method, in accordance with claim 32, characterised in that the step of flaring the distal end (36) of the skirt (31) of the inner container (30) comprises flaring an entire perimeter of the distal end (36) of the skirt (31) of the inner container (30) around a central longitudinal axis (4) of the tubular container (1), the distal end (36) of the skirt (31) of the inner container (30) remaining flared and in contact with the distal end (16) of the skirt (11) of the outer tube (10) throughout said entire perimeter.
 34. Method, in accordance with claim 32, characterised in that the step of flaring the distal end (36) of the skirt (31) of the inner container (30) comprises inserting a conical part (50) into the distal end (36) of the skirt (31) of the inner container (30) and deforming the distal end (36) of the skirt (31) of the inner container (30) against the distal end (16) of the skirt (11) of the outer tube (10).
 35. Method, in accordance with claim 32, characterised in that the step of inserting the inner container (30) comprises inserting the inner container (30) until the distal end (36) of the skirt (31) of the inner container (30) is flush with the distal end (16) of the skirt (11) of the outer tube (10).
 36. Method, in accordance with claim 32, characterised in that the step of inserting the inner container (30) comprises inserting the inner container (30) until a length (h1) of the distal end (16) of the skirt (11) of the outer tube (10) protrudes from the distal end (36) of the skirt (31) of the inner container (30).
 37. Method, in accordance with claim 32, characterised in that it further comprises the step of securing the distal end (36) of the skirt (31) of the inner container (30) to the distal end (16) of the skirt (11) of the outer tube (10) along at least part of a perimeter around a central longitudinal axis (4) of the tubular container (1).
 38. Method, in accordance with claim 37, characterised in that the step of securing the distal end (36) of the skirt (31) of the inner container (30) comprises welding, adhering or a combination thereof.
 39. Method, in accordance with claim 32, characterised in that the step of obtaining an outer tube (10) comprises obtaining the skirt (11) of the outer tube (10) by extrusion and forming the head (12) of the outer tube (10) through over-injection moulding onto the skirt (11) of the outer tube (10).
 40. Method, in accordance with claim 32, characterised in that the step of obtaining an outer tube (10) comprises obtaining the skirt (11) of the outer tube (10) by injection moulding and forming the head (12) of the outer tube (10) through over-injection moulding onto the skirt (11) of the outer tube (10).
 41. Method, in accordance with claim 32, characterised in that the step of obtaining an outer tube (10) comprises obtaining the outer tube (10) through a joint injection moulding of the skirt (11) and the head (12) of the outer tube (10).
 42. Method, in accordance with claim 32, characterised in that the step of obtaining an inner container (30) comprises obtaining the skirt (31) of the inner container (30) by extrusion.
 43. Method, in accordance with claim 32, characterised in that the step of obtaining an inner container (30) comprises obtaining the skirt (31) of the inner container (30) by injection moulding.
 44. Method, in accordance with claim 32, characterised in that the step of obtaining an inner container (30) comprises obtaining a laminate of a plastic or metal-plastic complex material, deforming the laminate until a tubular shape is obtained, sealing adjacent edges of the tubular shape to maintain the tubular shape and obtaining the skirt (31) of the inner container (30). 45-59. (canceled) 